Miniature rotary encoder

Abstract

A small rotary encoder capable of easily fitting a substrate into a proper position without using an adhesive or the like is provided. Slits are formed in an encoder case so that the encoder case is partially plate-spring shaped, a step portion and a claw portion are formed on the inner circumference of the encoder case, convex portions and concave portions that are combined with each other are formed on the inner circumference of the encoder case and a substrate, respectively. When the substrate is inserted into the encoder case, the encoder case is bent by the slits so that the substrate can be inserted into the encoder case. The substrate is inserted between the step portion and the claw portion, so that the substrate can be fitted into the encoder case, and the substrate is prevented from being incorrectly fitted in a circumferential direction, so that a position can be easily determined.

1. A small rotary encoder comprising a magnetic disk, a substrate where a sensor, a multiplying IC, or an output cable is mounted, and a cylindrical encoder case accommodating the magnetic disk and the substrate,
 wherein slits are formed in the encoder case, a claw portion that protrudes in a radial direction of the encoder case and a step portion that determines a position in an axial direction of the substrate, are formed in the inner circumference of the encoder case, and the step portion and the claw portion allow the substrate to fit into the encoder case. 
 
   
   
     2. The small rotary encoder of  claim 1 , wherein convex and concave portions which are combined with each other, are formed on the inner circumference of the encoder case and the substrate, respectively. 
   
   
     3. The small rotary encoder of  claim 2 , wherein the slits are hook shaped and are formed in a plurality of spots on the encoder case. 
   
   
     4. The small rotary encoder of  claim 1 , wherein the slits are hook shaped and are formed in a plurality of spots on the encoder case.